This invention relates generally to injection molding and deals more particularly with an improved method and apparatus for molding various types of articles such as clay pigeons and the like.
At present, clay pigeons are typically formed on complication molding machines which are operated by cam devices. These machines are usually circular in shape and require a large number of carefully timed movements of the various operating components. Consequently, such machines are highly complex and costly, as well as being difficult to maintain in proper working order. Furthermore, due to the arrangement of the mold and the manner in which the molding is carried out, the parts often exhibit "flashing", i.e., burrs and rough areas on the edges.
Other types of molding machines have similar drawbacks. For example, injection molding equipment of the type currently used to mold simple plastic articles requires high pressure injection of the molding material. As a result, complicated clamping devices and high pressureseals are necessary, and additional problems inherently associated with high pressure operation are encountered. It is common for machines of this type to be equipped with an insert piece having a small diameter orifice through which the material is forced into the mold cavity. The material located in the orifice forms a sprue on the part which is difficult and expensive to remove.
It is the primary object of the present invention to provide an improved method and apparatus for molding clay pigeons and other articles such as chinaware, ceramic items, and various types of plastic products.
Another object of the invention is to provide a method and apparatus of the character described wherein the molded article is easily released from the mold. This important feature is achieved by providing a pin member in the injection passage which is heated to a high enough temperature to assure proper release of the part while avoiding undue damage to it.
Yet another object of the invention is to provide a method and apparatus of the character described which avoids the formation of sprues, flashing, or other significant imperfections on the part.
A further object of the invention is to provide a molding machine of the character described in which the temperatures and movements of the parts are accurately controlled.
An additional object of the invention is to provide a molding machine of the character described which operates at relatively low pressure.
A still further object of the invention is to provide a molding machine of the character described which is simple and economical to construct and which operates reliably without undue maintenance requirements.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.